A variety of diffusion transfer color photographic integrated film units are heretofore known in the art, for example, in U.S. Pat. Nos. 3,415,644 3,415,645, 3,415,646, 3,647,437, 3,635,707 and 3,756,815, and Canadian Pat. Nos. 928,559 and 674,082.
In these units an image receiving layer is so designed as to be parmanently integrated with a silver halide emulsion layer or layers.
Other types of diffusion transfer color photographic film unit, for example so-called "peel-apart type", are known e.g., in U.S. Pat. Nos. 2,983,606, 3,362,819 and 3,362,821. In this type of unit, an image receiving layer is peeled apart from silver halide emulsion layers after completion of dye image-transfer process.
In these film units mentioned above, the following disadvantages are known when internal latent image type emulsions are used to directly give positive images. Namely, a fogging agent is usually used in this type of emulsion in order to render fog to unexposed silver halide particles during development. For instance, when such nonadsorptive type fogging agents as disclosed in U.S. Pat. No. 3,227,552 are used, a large amount of the fogging agent must be used to obtain sufficient dye image density, whereby the fogging agent undergoes decomposition action and generate a large amount of bubbles and thereby exert adverse influence upon photographic properties of the resulting positive image. Accordingly, the fogging agent is usually used in a small amount in order to avoid such problem, but in that case sufficient density cannot be obtained in the resulting dye image. On the other hand, when such adsorptive type fogging agents as is disclosed in Japanese Patent Publication Laid-Open-to-Public Inspection No. 53-20318/1978, are used, fogging effect may be effected even with the addition of a very small amount thereof, but, in this case, a sufficient dye image density cannot be obtained even with an increased concentration.
As a means to overcome such deffects, there is disclosed a technique in Japanese Patent Publication Laid-Open-to-Public Inspection No. 52-127233/1977, wherein glycols and/or amino alcohols are used in a processing composition for a diffusion transfer color photographic film unit comprising an internal latent image type direct positive silver halide emulsion and a non-diffusible dye releasing redox compound. These compounds have, however, such drawbacks that their image density improving effect is generally insufficient, if not at all, and that the use of the amino alcohols often result in formation of color stain.